Abstract
Many complex networks from the World Wide Web to biological networks grow taking into account the heterogeneous features of the nodes. The feature of a node might be a discrete quantity such as a classification of a URL document such as personal page, thematic website, news, blog, search engine, social network, etc., or the classification of a gene in a functional module. Moreover the feature of a node can be a continuous variable such as the position of a node in the embedding space. In order to account for these properties, in this paper we provide a generalization of growing network models with preferential attachment that includes the effect of heterogeneous features of the nodes. The main effect of heterogeneity is the emergence of an "effective fitness" for each class of nodes, determining the rate at which nodes acquire new links. The degree distribution exhibits a multiscaling behavior analogous to the the fitness model. This property is robust with respect to variations in the model, as long as links are assigned through effective preferential attachment. Beyond the degree distribution, in this paper we give a full characterization of the other relevant properties of the model. We evaluate the clustering coefficient and show that it disappears for large network size, a property shared with the Barabási-Albert model. Negative degree correlations are also present in this class of models, along with nontrivial mixing patterns among features. We therefore conclude that both small clustering coefficients and disassortative mixing are outcomes of the preferential attachment mechanism in general growing networks.
Highlights
In the last 10 years statistical mechanics has made great advances [1,2,3,4,5,6] in the understanding of the dynamics and the characteristic structural properties of complex networks
In order to account for these properties, in this paper we provide a generalization of growing network models with preferential attachment that includes the effect of heterogeneous features of the nodes
We evaluate the clustering coefficient and show that it disappears for large network size, a property shared with the Barabasi-Albert model
Summary
In the last 10 years statistical mechanics has made great advances [1,2,3,4,5,6] in the understanding of the dynamics and the characteristic structural properties of complex networks. Connectivity between and within modules depends on tissue and species [19] and should be taken into account in realistic models of coexpression networks In light of these results it is necessary to understand how similarity, spatial embedding, modular structure, or other features might change the nowadays classic description of growing networks following preferential attachment [20]. In this mechanism, new nodes are added at a constant rate and connected to existing nodes of the network.
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